104 



THE RUSTIC PERIOD. 



CHAP. 



probably its representative. That stone has usually been regarded 

 as the base of the true lias. 



The section of contemporaneous beds at Wainlode Cliff, near 

 Tewkesbury, was examined by Mr. Strickland , and Mr. Brodie d 

 has given a statement of the insect and other organic remains 

 found there. The series may be thus epitomized, drawing the line 

 for the base of the lias as before stated : 



Oyster beds. 



Monotis bed. 



Estheria bed. 



Bone bed. 



Strata. ft. in. Fossils. 



LlASSIC. 



Black clay .....30 

 Limestone, hard, blue, with Ostrea and 



Modiola minima . . . .04 

 Shale, yellow ; traces of fucoids . o 10 

 Limestone, grey and blue, with insects o 5 



KILETIC. 



Marly clay 53 



Limestone, hard, yellow, nodular, with 



Estherise, Cyprides, Unio, plants, 



and fish-scales ....07 

 Yellow clay .....90 



Black shale 3 o 



Grey stone, with fucoidal impressions 



above, and scales and teeth of fishes o i 

 Black slaty clay .... I 6 

 Pyritous stone containing Pecten and 



other shells . . . .04 



Black shale 80 



Bone bed, hard pyritous stone, with i 



bones, scales, and teeth of fishes . I o 3 Bone bed. 

 Thin sandstone, with Pullastra . J 

 Black shale .....20 

 Total thickness of rhsetic beds 30 o 



POIKILITIC. 



Green and red marls occur below. 



One other section may be given, that which Messrs. Graves and 

 Kershaw obtained by sinking through the strata at the base of 

 their lias quarry at Wilmcote, near Stratford-on-Avon e . 



The beds here counted by Dr. Wright as of the Westbury group, 

 begin with the Estheria bed, and fit the classification already given ; 

 a small addition is made of the thin clay and layer above it. 



Geol. Proc. iii. p. 586 ; iv. p. 16. d Fossil Insects, p. 58. 



6 Dr. Wright has recorded the result of this interesting experiment, Geol. Soc. 

 Journal, 1860. 



